1. Field of the Invention
The present invention relates to an apparatus and a method for applying a fluid which can be used in a production process of electronic components, household electrical appliances, etc. for discharging a constant amount of various kinds of liquid such as adhesives, solder paste, phosphors, grease, paint, hot melt, medicines, foods, etc.
2. Description of the Related Art
While a liquid discharge apparatus (dispenser) has been conventionally used in a variety of fields, a technique of highly accurately and stably controlling to discharge a minute amount of fluid material becomes required in accordance with the current need for electronic components to be made compact with a high recording density. In the field of, for example, a surface mounting technique (SMT) for electronic components, high-speed, high-density, high-quality and automatic mounting into a micro-size is required and, the contents of the requirement to the dispenser are summarized as follows:
(1) To obtain a highly accurate application amount while holding the application amount for each time minute;
(2) To shorten a discharge time, i.e., to discharge, shut and start the discharge at high speeds; and
(3) To meet highly viscous fluids in powders.
In order to discharge a liquid of a minute flow rate, dispensers of an air pulse system, a groove type, and the like have been practically used heretofore.
Among the dispensers of the aforementioned types, the dispenser of the air pulse system as indicated in FIG. 8 has been widely employed. The dispenser of this system supplies a constant amount of the air supplied from a constant pressure source 20 into a cylindrical container 10 in pulses, thereby discharging a constant amount of a liquid 25,corresponding to an amount of a pressure rise in the container 10 through a nozzle 12.
The dispenser of the air pulse system is poorly responsive when discharging the fluid 25. Meanwhile, a screw type dispenser, such as a viscous pump, has also been put in practical use. The dispenser of this type generally adopts a structure wherein an object to which the liquid or the like is to be applied by the dispenser, and the dispenser are made relatively movable in X, Y and Z directions, so that the liquid can be applied linearly by moving the object to be applied and the dispenser relatively in either the X or the Y direction while discharging the liquid from the dispenser.
In the above-described conventional application method, as is apparent from FIGS. 9C and 9D, a discharge control signal for letting the dispenser carry out a discharge operation is set to rise and fall with the same timing as a timing of a rising edge and a falling edge of a movement control signal for moving the dispenser and the object to be applied in the X or Y direction. It takes a predetermined amount of time before a constant amount of the fluid is discharged after the discharge control signal is supplied in the above dispenser, as is shown in FIG. 9D. Similarly, it takes a predetermined period of time before the fluid discharge is actually stopped after a signal instructing stopping the discharge is supplied. Therefore, an application state of the fluid from the dispenser to the object to be applied becomes one such as is represented in FIG. 9A. Specifically, the application starts at an application start part 30 with the time delay from the rise of the discharge control signal, having an application amount gradually increased, whereas the fluid is turned to a mass shaped at a discharge termination part 32 because of the application amount being amassed by the time difference between the signal and the actual discharge stop. In other words, as indicated by a dotted line in FIG. 9A, it is difficult for the conventional fluid application apparatus to form a fixed fluid application region and obtain a uniform application amount over an entire range of the fluid application region. The reason for this is that starting and stopping the discharge of the fluid having fluidity is subject to a time lag, while moving the object to be applied and the dispenser in the X or Y direction is a mechanical operation without a time lag. Although, for example, an operation timer can be set to delay the movement in the X or Y direction, to stop the discharge earlier, etc. for solving the above problem and obtaining a normal application state, it is difficult to match the fluid discharge with the mechanical operation particularly in the case of a fluid which is viscous, and consequently the application state still varies.
In the field of forming circuits which increasingly becomes highly accurate and superfine; and in the fields of manufacturing processes of forming electrodes and ribs of image tubes such as PDPs (plasma display panels), CRTs, etc., applying a sealing material of liquid crystal panels, and manufacturing optical discs or the like; the following requirements are made in relation to a fine application technique:
(1) To be able to quickly stop the application after continuous application and to immediately restart the continuous application a short time later. It is ideal to control a flow rate in the order of, for example, a 0.01 second; and
(2) To be able to meet fluids in powders, for example, without crushing and breaking the powder, clogging a channel, or the like trouble by mechanically shutting the channel.
An object of the present invention is therefore to provide an apparatus and a method for applying a fluid, while eliminating the above-described problems, whereby an application amount of the fluid to be applied can be kept stable even at a fluid discharge start part and a fluid discharge termination part.
In order to accomplish the above objective, the present invention has following constructions.
According to a first aspect of the present invention, a fluid application apparatus, which is provided with an application head including:
a cylindrical discharge member for carrying out a discharge operation for a fluid to be applied;
a storage member shaped like a recess for storing the discharge member via a first gap in a diametrical direction of the discharge member and a second gap in an axial direction of the discharge member, having a discharge passage extending along a center axis of the discharge member to be opened to the second gap for discharging the fluid supplied to the first gap and moved to the second gap to the outside;
a moving device having an electro-magnetostrictive element for controlling starting and stopping the discharge of the fluid through the discharge passage to the outside by moving the discharge member along the axial direction;
a rotating device for rotating the discharge member along a circumferential direction of the discharge member; and
a movement groove formed to at least either a circumferential face of the discharge member facing the first gap or a first opposite face opposite to the circumferential face of the storage member for moving the fluid present at the first gap to the second gap by the rotation of the discharge member by the rotating device, and
a control unit connected to the moving device and the rotating device for carrying out to the moving device an operational control of moving the discharge member in a discharge direction along the axial direction when the fluid is to be discharged through the discharge passage to the outside.
The control unit can also control the rotating device to rotate the discharge member when the fluid is to be discharged through the discharge passage to the outside.
The above control unit can further control the rotating device so as to stop the rotation of the discharge member, and at the same time, control the moving device so as to move the discharge member in a direction opposite to the discharge direction along the axial direction when the fluid discharge through the discharge passage is to be stopped.
The fluid application apparatus can be further provided with a supporting member for supporting an object to which the fluid is to be applied by the application head, a lift device for relatively moving the application head and the supporting member up and down, and a horizontal moving device for relatively moving the application head and the supporting member in a horizontal direction orthogonal to the lifting direction by the lift device. In a fluid application operation from the application head to the object to be applied, after the control unit makes the lift device relatively move the application head and the supporting member up and down to be close to each other, at a fluid discharge start time, the control unit executes operational controls to the rotating device and the moving device of starting the rotating the discharge member and the moving the discharge member in the discharge direction, and at the same time an operational control to the horizontal moving device of starting the relatively moving the application head and the supporting member in the horizontal direction; until the fluid discharge through the discharge passage is stopped after the discharge start, the control unit executes an operational control to the rotating device of the rotating the discharge member and an operational control to the horizontal moving device of the moving the application head and the supporting member; and at a stop time of the fluid discharge, the control unit executes an operational control to the rotating device of stopping the rotating the discharge member, an operational control to the moving device of stopping the moving the discharge member, and at the same time an operational control to the horizontal moving device of stopping the relatively moving the application head and the supporting member in the horizontal direction as well as an operational control to the lift device of relatively moving the application head and the supporting member up and down to separate from each other.
According to a second aspect of the present invention, there is provided a fluid application method carried out with the use of an application head which includes a cylindrical discharge member for carrying out a discharge operation for a fluid to be applied;
a storage member shaped like a recess for storing the discharge member via a first gap in a diametrical direction of the discharge member and a second gap in an axial direction of the discharge member, having a discharge passage extending along a center axis of the discharge member to be opened to the second gap for discharging the fluid supplied to the first gap and moved to the second gap to the outside;
a moving device having an electro-magnetostrictive element for controlling starting and stopping the discharge of the fluid through the discharge passage to the outside by moving the discharge member along the axial direction;
a rotating device for rotating the discharge member along a circumferential direction of the discharge member; and
a movement groove formed to at least either a circumferential face of the discharge member facing the first gap or a first opposite face opposite to the circumferential face of the storage member for moving the fluid present at the first gap to the second gap by the rotation of the discharge member by the rotating device,
the method comprising:
moving the discharge member in a discharge direction along the axial direction when the fluid is to be discharged through the discharge passage to the outside.
In the above-described fluid application method of the second aspect, the discharge member can be rotated, and moreover moved in the discharge direction when the fluid is to be discharged through the discharge passage to the outside, while the rotation of the discharge member is stopped and the discharge member can also be moved in a direction opposite to the discharge direction along the axial direction when the fluid discharge from the discharge passage is to be stopped.
Further, the fluid application method of the second aspect enables an operation control, whereby, when application from the application head to an object to which the fluid is to be applied by the application head is to be carried out, after the application head and the object to be applied are relatively moved to be close to each other, at a fluid discharge start time, the rotation of the discharge member and the movement of the discharge member in the discharge direction are started, and at the same time, the application head and the object to be applied are started to be relatively moved in a horizontal direction; before a stop of the fluid discharge through the discharge passage after the discharge start, the rotating the discharge member and, the moving the application head and the supporting member are carried out; and at a stop time of the fluid discharge, the rotating the discharge member is stopped, the moving the discharge member is stopped, and at the same time an operational control of stopping the relative movement of the application head and the object to be applied in the horizontal direction as well as relatively moving the application head and the object to be applied up and down to separate from each other is carried out.
According to the fluid application apparatus of the first aspect and the fluid application method of the second aspect of the present invention, there are provided the application head and the control unit, so that the operation is controlled to move the discharge member in the discharge direction along the axial direction when the fluid is to be discharged. By adopting the above arrangement, the fluid application apparatus having the moving device including the electro-magnetostrictive element to the application head is enabled to control the fluid discharge, that is, temporarily increase a discharge amount of the fluid at a fluid discharge start part.
When the fluid is to be discharged, the control unit may control rotation of the discharge member and also move the discharge member in the discharge direction along the axial direction. This arrangement enables the fluid to be supplied to the discharge member through the rotation of the discharge member, thereby the fluid being able to be discharged more smoothly.
When the discharge is to be stopped, the control unit controls to stop the rotation of the discharge member and move the discharge member in the opposite direction to the discharge direction. Because of the above arrangement, it becomes possible to temporarily increase the discharge amount of the fluid at the fluid discharge start part, and suppress the fluid so as not become stringy and prevent an application amount from increasing at a fluid discharge end part. The application amount of the fluid can be stabilized both at the fluid discharge start part and the fluid discharge end part.
There are also provided the lift device and the horizontal moving device, thereby moving the object to be applied in the horizontal direction in correspondence to the fluid discharge start operation and the fluid discharge termination operation by the discharge member. The application amount of the fluid to be applied to the object to be applied is accordingly stabilized even at the fluid discharge start part and the fluid discharge end part.